William a



W. AY. GWYNN.

SPARK PLUG.

Armcmon man sPT..19|9.

Patented Apr. 6, 1920.

n. n n J mw m ma ,a J m ,w M w d W@ a 13 d, 6 j Q5 UNITED sfrats PATENT OFFICE.

WILLIAM A. GWYNN, 0F ST. LOUIS, MISSOURI, ASSIGNOR TO SUSIE E. GWYNN, OF ST.

LOUIS, MISSOURI.

SPARK-PLUG.

Specification of Letters Patent.

Patented Apr. 6, I1920.

To all "whom, t may concern.'

Be it known that I, WILLIAM A. GwvNN, a citizen of the United States, residing in the city of St. Louis and State ot' Missouri, have invented new and use fnl Improvements in Spark-Plugs, of which the followin is a specification.

his invention relates to spark plugs intended more particularly for use in antomobiles and has the same general character illustrated and described in application filed of even date herewith.

The objects of the present invention are to provide means lor insuring the correct distance of Spark gap on the interior ot' the plug and for maintaining this distance under all normal conditions ot' operation.

The invention in its broad aspect. so far as it concerns the plug as a whole, is covered in the companion application referred to, and the present invention is directed to novel means for providinpi a spark `rap in the interior of the plug, located in one of the terminal wires thereof.

In the accompanying drawings,

Figure 1 is a view in elevation of a spark plug constructed according to my invention:

Fig. 2 a central vertical sectional view thereof;

Fig. 3 is a broken view in central vertical section illustrating,r a modified construction olt the spark gap terminals; and

Fig. 4 is a similar view illustiatiingr a further modification.

Referring to the drawing, the numeral l indicates the upper member of a spark plug casinlLv which is preferably provided with an integral nut 2 and has screwed on its lower end at 3 the lower casing member l. which carrieav at its lower end one of the spark plugr terminals 5. The casing' member 4 is* provided on its interior with an an nular shoulder which is adaptedto snpport a gasket 7 on which rests a shouldered portion ot' a porcelain member S. Above this shouldered portion lhc interior of the casing -l and lhe porcelain S are correspond ingly| shouldered to receiv'.` a lgasket Si which is adapted lo bc engaged b v the lower end ol lhc casing;r nlcnibcr l` which thin; holds the t porcclaln member hrnily lo ils seal b. llc` upper portion ol' `said porcelain member p roii-cts into the lower portion ol' the caslngll member l and is provided al Ils upper end with a relatively deep recess, the bottom of which is flat to provide a seat 11. Secured 1n the porcelain. member 8 is a terminal Wire 12 which projects downwardly into and thi-(nigh a recess 13 provided in the lower end ot` the, porcelain member 8, and has `its lower end located at a sparkingdistance from the terminal The upper end of the terminal wire 12 is located at a certain elistance below thc plane of the seat 11. The numeral 14 indicates,l a porcelain plug which is mounted in the upper end of the easingv member 1, and has` centrally secured therein a conductor 15 in the form of a har, the lower end portion of which bar projects downwardly a certain distance within the recess 10 and is centrally recessed from its lower end upward as indicated at 16. Frictionally engaging in the recess 16 is a stem 17 which carries at its lower end a flat plate 1S adapted to rest upon the seat 11. The upper end of the conductor 15 is provided with the usual binding screw 19.

From the construction described, it Will be seen that I am enabled to provide a Spark gap in the interior of the plug of a definite extent of separation, without liability of bringing the two terminal members 12 and 18 in contact when ariseinlolinlgr the Spark plug. and also to insure the said Spark gap being maintained under all normal conditions ot' operation. That is to say, the extent of the spark `gap may beiceurately determined by the distance the upper end of the terminal wires, 12 is located below the seat 11 in the porcelain member S. When the porcelain plug 1-1 is placed in position in the casing' 1. the terminal plate 18 must rest upon the seat 1l and is prevented from approaching any nearer to the end of the terminal 12.

ln assembling' the parts, the stem 17 will slide upwardhr under force in recess 16, so that no nicc adjustment ot' the length of the har lf with respect to the end of the terminal wire l2 is required. .\t thepsame time` the friclioual engagement of the stem lT with the wall ol the recess 1G is suf Iicienll)` great to` prevent movement of the plate 1H a l'tcr the parts have been a-djusted in position. llowevcr.l to provide against thc contingency ol' such movement, I may adopt the construction shown in Fig. 4. in which a coil springr 20 is placed in the l'ecess 16 to press on the stem 17 and thereby constantly force the terminal plate 18 into en gement with the seat 11.

I; Fig. 3, a still further modification is shown, 1n which the terminal plate 18 is provided with a hollow cylindrical extension 21 which is adapted .to slidably receive the lower end portion 22 of the conductor 15, and a. coil spring 23 is positioned between the u per end of the extension 21 and a shoul er 24 on the conductor 15, which engages the bottom of the plug 14. It will readily be seen that the extension 21 will slide yover the end 22 of the conductor in assemblin the parts, and that the spring 23 will ho d the terminal plate 18 in engagement with the seat 11.

1 claim:

1. In a'spark plug, the combination with a spark plug casing, e porcelain member mounted therein and provided in itsupper end with a recess affording a seat, a terminal wire secured in said porcelain inember and having its upper end positioned below the plaine of said seat, and a porcelain plug mounted in the upper end of said casing and having secured therein a conductor extending into said recess and pro vided at its lower end with a terminal plate resting upon said seat.

2. A spark plug according to claim 1, in which the terminal plate is relatively movable with respect to said conductor.

.3, A spark plug acoording to claim 1, in which the lower end of the conductor is re cessed :ind the terminal plate is provided with a' stem frictionally engaging in said recess. 4

4. A spark plug 'accordingr to claim 1, in which the terminal plate is slidably mounted with respect to said conductor and is yieldingly pressed by a spring against its seat.

A spark plug according to claim 1, in which the lower end of said conductor is recesse'd ant] provided with a coil spring in selted in said recess and the terminal plattl is provided with a stem working in said re cess against said spring.

In testimony whereof, I have hereunto set my hand.

WILLIAM A. GVVYNN. 

